Flash lamp



June 10, 1952 H. P. KEUKENS ETAL 2,599,644

FLASH LAMP Filed Feb. 28, 1950 HP Keukens &L.H.Vcrbeek AGENT Patented June 10, 1952 FLASH LAMP I-lubertus Pieter Keukens and Leo Henricus Verbeek, Eindhoven, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application February 28, 1950, Serial N 0. 146,796

In the Netherlands March 5, 1949 3 Claims.

This invention relates to electric lamps of the photographic flash-light type the bulb of which contains substances having an actinic reaction on each other upon ignition and is coated with a lacquer layer on the inside as well as on the outside. Such lacquer layers are known to be used to avoid the risk of the bulb bursting upon ignition of the flash-light lamp and to hold the splinters as far as possible in the event of breakage of the bulb.

The invention permits of ascertainin in a simple manner whether the two lacquer layers are present on the bulb wall, so as to prevent delivery of insufficiently lacquered flash-light lamps to the user.

According to the invention, for this purpose, the two lacquer layers are coloured with substantially complementary colours, so that the bulb of the flash-light lamp is substantially colourless, so far it is coated with the two lacquer layers. If one of the two lacquer layers is missing, the colour of the remaining lacquer layer becomes perceptible, so that any local absence or complete absence of the lacquer layer can readily b ascertained.

In order to avoid as far as possible undue increase in light absorption by the colours of the lacquer layers, the colour intensity should be low.

For colouring the lacquer, use may be made of colouring substances which dissolve in the solution of the lacquer with which the bulb of the flash-light lamp is coated, or else, finely ground pigment colouring substances may be suspended in the lacquer solutions.

The invention will be described more fully with reference to the following example.

Example The bulb of the flash-light lamp is sprayed on the inner side with a solution of polyvinylacetate, such as that sold under the trade name Vinapaslak, in which 0.03 percent by weight, calculated on the basis of the dry lacquer, of Paris blue is suspended, so that after spraying a layer.

Paris blue is a good chemische Industrie or by J. R. Geigy" respectively, both having their seat at Basel.

The internal lacquer layer is blue and the external lacquer layer is orange-coloured. A flashlight lamp, the bulb of which is coated with these two layers is colourless.

The single figure of the accompanying drawing shows, by way of example, a flash-light lamp, the

bulb of which is provided with an internal and an external lacquer layer, which are coloured in accordance with the invention.

Reference numeral I designates a glass bulb coated internally with a lacquer layer 2 and externally with a lacquer layer 3. Reference numeral 4 designates the lamp cap of the flashlight lamp, which is connected to a supply wire 5. A supply wire 6 is connected to the central contact of the lamp base I. The supply wires are connected at 8 by a filament by which an ignition paste 9 is supported. The actinically reacting material H1 is constituted by a wire of an aluminium-magnesium alloy which contains 7 percent by weight of magnesium and is housed in the bulb. which is filled with oxygen to a pressure 01' 50 cms. of mercury.

What we claim is:

1. A flash-light lamp comprising a bulb, an actinically reacting material therein, complementary colored lacquer layers on the external and internal surfaces of said bulb to make said bulb appear substantially colorless.

2. A flash-light lamp comprising a bulb, an actinically reacting material therein, a colored lacquer layer on the outer surface of said bulb and a colored lacquer layer on the inner surface of said bulb, the colors of said layers being complementary so that the bulb appears colorless.

3. {1 flash-light lamp comprising a bulb, an actinically reacting material therein, a blue-colored lacquer layer on the one surface of said bulb and an orange-colored lacquer layer on the other surface of said bulb to make said bulb appear substantially colorless.

HUBERTUS PIETER KEUKENS. LEO HENRICUS VERBEEK.

REFERENCES CITED The following references are of record 11 file of this patent: i the UNITED STATES PATENTS Apr. 4, 1944 

2. A FLASH-LIGHT LAMP COMPRISING A BULB, AN ACTINICALLY REACTING MATERIAL THEREIN, A COLORED LACQUER LAYER ON THE OUTER SURFACE OF SAID BULB AND A COLORED LACQUER LAYER ON THE INNER SURFACE OF SAID BULB, THE COLORS OF SAID LAYERS BEING COMPLEMENTARY SO THAT THE BULB APPEARS COLORLESS. 